Control device



Sept. 2, 1958 J. L. HARRIS CONTROL DEVICE Filed June 28, 1950 NVENU United htates Patent CONTROL DEVICE John L. Harris, Whitefish Bay, Wis.

Application June 28, 1950, Serial No. 170,929

8 Claims. (Cl. 200-38) This invention relates to automatic control apparatus and is more particularly concerned with timers of the manual reset type. The primary object of the invention is to provide a timing mechanism which is simple and rugged in construction and which is easy to operate by the user.

A further object of the invention is to provide atimer in which the switch mechanism is operated at the end of the resetting stroke so as to eliminate the variable of the time of manual resetting.

A further object of the invention is to provide an interval timer mechanismwhich is adapted to be set for varying time periods or to accurately repeat predetermined periods for which the mechanism is set.

Another object of the invention is to provide an interval timer mechanism in which a single switch or control device may be operated by the timing mechanism or may be operated independently of the timing mechanism.

The present invention constitutes an improvement in the switching mechanism of the timer disclosed in my application Serial No. 42,119, filed August 2, 1948.

. A further object of the invention is to provide a switching mechanism requiring a small operating force relative to its switching capacity, andwhich is simple in construction. a.

For a complete disclosure of the invention, reference is made to the accompanying drawings in which Fig. 1 is a front view of a complete timer,

. Fig. 2 is a side view, and

Fig. 3 is a fragmentary view of one form of switching mechanism embodying the invention.

Referring to Fig. 1, reference character 1 indicates a mounting plate. Mounted on plate 1 and separated therefrom by means of spacers 2 and 3 is a back plate 4. This plate carries a synchronous timing motor 5 having a final shaft carrying a pinion 6. This pinion 6 meshes with a gear 7 which is carried on a shaft 8. The shaft 8 is freely supported in the front plate 1 and the black plate 4, and extends forwardly of plate 1. The free end of shaft 8 carries a hub 9 which in turn carries a dial 10 and an operating member 11. As shown more clearly in Fig. 2 the hub 9 is provided with a shoulder adjacent its front end, and the dial 10 and operating member 11 are pressed against this shoulder by means of a friction spring 12. This construction permits the dial and operating member to be adjusted or moved on the hub. This arrangement is disclosed in detail in my application Serial No. 42,119, filed August 2, 1948.

Secured to the back plate 4 by means of rivets 13 is a switch plate 14 preferably of phenolic material. Mounted on this switch plate is a contactbracket 15carrying a contact 16. Also mounted on the plate 14 is a switch blade bracket 17 which carries switch blades 18 and 19. The switch blade 18 extends across the panel 14 and is provided with a contact 20 which cooperates with con-. tact 16 to complete a circuit from the line terminal 15 to the load terminal 17. The switch blade 19 extends to the right and then upwardly to engage a pin 25. As

ice

shown in Fig. 2, the pin is pressed in the panel 14 and is connected by a lead 26 to one terminal. of the timer motor 5.

The switch blades 18 and 19 are operated by a cam 27. This cam is mounted on a shaft 28 which is freely supported between the plate 1 and switch panel 14. This shaft 28 extends forwardly of the mounting plate 1 and carries an operating member or pointer 29. The member 29 is provided with an on cam surface 30 which is adapted to be engaged by a rearwardly extending pin 31 on the manual operator 11. Member 29 is also provided with an o cam surface 32 which is adapted to be engaged by a pin 33 extending rearwardly of the dial.

As shown more clearly in Fig. 3, the switch blade 18 is formed with an offset portion 35 adjacent the cam. With the parts in the positions shown, the pointer 29 is in the off position which causes the cam to be in the position of Fig. 3 in which contacts 16 and 20 are open and switch blade 19 engages the pin 25. .When the operator wishes to start a timed period, the member 11 is set to the required time on the dial 10 and the entire dial assembly is rotated clockwise by dialing the rnember 11. At the end of the dialing stroke the pin 31 engages the cam surface 30 of member 29, this causing the shaft 28 and cam 27 to be rotated counter-clockwise. During this movement the section 36 of the cam engages the offset 35 of the switch blade and rides up the offset thus causing the contacts 16 and 20 to engage. The circuit is thus completed from the line to the load terminals. A circuit for the timer motor is also completed through switch blade 19 and contact 25. Thus the timer motor is energized simultaneously with the load and rotates the shaft 8 counter-clockwise. As the end of the timed period approaches, the pin 33 on the dial engages the Off cam surface of the lever 29 and rotates the shaft 28 clockwise. During initial movement of the shaft, the sectionr36 of cam 27 merely rides along the top section 38 of the switch blade. However, at the end of the timed period, the section 36 of the cam rides down the offset portion 35 of the switch blade. At this time the cam snaps to its Off position permitting the contacts 16 and 20 to open. This de-energizes both the load and the timing motor.

In some cases it is desirable to operate the load for an extended duration of time. When this is desired the pointer 29 is moved to the position marked Look on. In this position the lobe 39 of cam 27 engages the switch blade and causes contacts 16 and 20 to re-engage. At the same time the portion 40 of the cam engages switch blade 19 and forces it away from the contact 25. This breaks the timer motor circuit so that the timer does not run even though the load is energized. The load will therefore remain energized indefinitely until the pointer 29 is moved from Look on back to Off.

An important feature of the invention is the arrangement of the switch blade with the offset portion between its ends and arranged to be engaged by the cam. This arrangement provides a very simple snap action movement from On to Off positions. This arrangement further provides a relatively heavy duty switch which is operable by a slight amount of power. It should be noted that as the cam rides up the offset portion, its first action is to cause contacts 16 and 20 to engage. After the contacts engage, the cam drives the switch blade still further and thus flexes the blade and causes a slight rocking of contact 20 on contact 16. This provides for a slight wiping action to keep the contacts clean. in addition, this flexure of the switch blade 18 after the contacts engage, builds up into the blade a force tending to pry the contacts open. This prying force is many times greater than the force applied by the cam to the center of the blade. As a result if the contacts should weld together upon engagement, the prying force is sufficient to break them loose when the cam is moved to the Off position. The switch therefore serves to carry a relatively heavy load as compared with the operating forces required. Y

While I have shown and described a preferred form of the invention, it will be seen that various modifications may be'made without departing from the spirit and scope of the invention. It is desired, therefore, to' be limited only by the appended claims.

What is claimed is:

1. In a switch construction, the combination of, a spring switch blade anchored at one end and provided with a contact surface substantially spaced from said anchored end, said switch blade being formed With an offset substantially midway between said anchored end and the contact surface, a rigidly mounted stationary contact arranged to be engaged by said contact surface, a freely supported rotatable cam arranged to engage the offset of the switch blade so as to operate theswitch from open position to closed position as the cam is rotated in one direction and to operate the switch from closed position to open position as the cam is rotated in the opposite direction, and means for rotating the cam in either direction.

2. In a switch construction, the combination of, a spring switch blade anchored at one end and, provided with a contact surface substantially spaced from said anchored end, said switch blade being formed with an offset substantially midway between said anchored end and contact surface, a rigidly mounted stationary contact arranged to be engaged. by said contact surface,'a freely supported rotatable cam having a first portion arranged to engage the offset of the switch blade so as to operate the switch from open position to closed position as the cam is rotated in one direction and to operate the switch from closed position to open position as the. cam isrotated in the opposite direction, said cam haying a'second portion arranged to engage the switch blade in a manner to return the switch from open position to closed position upon continued rotation of the cam in said opposite direction, and means for rotating the cam in either direction.

3. In a switch construction, the combination of. first and second switch blades each anchored at one end, said blades having free ends substantially spaced apart, and having movable contact surfaces, stationary contact surfaces arranged for cooperation with said. movable contact surfaces, a single rotatable cam located between the switch blades for engagement with the same, said cam having an intermediate position and two terminal positions, one on each side of the intermediate position, said cam being formed to open one set of contacts only in the intermediate position and to close said one set of contacts upon movement in either direction from the intermediate position, said cam also being arranged to open the other set of contacts in one only of said terminal positions.

4. In a switch construction, the combination of, a single switch blade support, first and second switch blades each anchored at one end to said single support, said blades having free ends substantially spaced apart, and having movable contact surfaces, stationary contact surfaces arranged for cooperation with said movable contact surfaces, a single rotatable cam located between the switch blades, said cam having an intermediate position and two terminal positions, one on each side of the intermediate position, said cam being formed to open one set of contactsonly in the intermediate position and to close said one set of contacts upon movement in either direction from the intermediate position, said cam also being arranged to open the other set of contacts in one only of said terminal positions.

5. In an electric timing mechanism, the combination of, an electric timing motor, a rotatable cam shaft, means for rotating said cam shaft either manually or by said timing motor, said shaft having an intermediate off position and two on positions, one on each side of said off position, first and second switch blades each anchored at one end and extending on diflferent sides of the cam shaft, said switch blades having movable contact surfaces, stationary contact surfaces arranged for cooperation with the movable contact surfaces, a cam mounted on the cam shaft between said switch blades, said cam being arranged so that upon movement from one on position to the other, it opens and recloses one set of contacts, said cam also being arranged to close the other set of contacts when in one of said on positions, and to open said other set of contacts when in the other on position, said one set of contacts controlling a load, and the other set of contacts controlling the timing motor.

6. In a timing mechanism, the combination of, a timing motor, a timing shaft rotated by the timing motor, a cam mounted for rotation on an axis spaced from and parallel with the timing shaft, lost motion drive means between the cam and timing shaft, a spring switch blade anchored at one end and provided with a contact substantially spaced therefrom, a stationary contact arranged to be engaged by the switch blade contact, said switch blade being biased in a direction tending to open the contacts and having an offset therein substantially spaced from the anchored end and the contact, said cam having an abrupt working surface and being located on the side of the switch blade opposite said stationary contact and'arranged so that said abrupt working surface engages the blade at the offset, said cam also being provided with a throw greater than required to engage the contacts, whereby upon rotation of the cam in one direction, it first closes the contacts and then bows the blade to rock the movable contact and provide a prying force tending to break the contacts loose when the cam is moved in the opposite direction.

7. In a timing mechanism, the combination of, a timing motor, a timing shaft rotated by the timing motor, a, cam mounted for rotation on an axis spaced from and parallel with the timing shaft, lost motion drive means between the cam and timing shaft, a spring switch blade anchored at one end and provided with a contact substantially spaced therefrom, a stationary contact arranged to be engaged by the switch blade contact, said switch blade being biased in a direction tending toopen the contacts and having an offset therein substantially spaced from the anchored end and the contact, said cam having an abruptworking surface and a generally circular high portion, said cam being located on the side of the switch blade opposite said stationary contact and arranged so that said abrupt working surface engages the switch blade at the offset, said cam also being provided with a throw greater than required to engage the contacts and with an angle of motion sufficient to permit the circular high portion thereof to ride on the top of the offset, whereby upon rotation of the cam in one direction, it first closes the contacts, then bows the blade to rock the movable contact and provide a prying force tending to break the contacts loose, and finally engages the blade with its generally circular high portion, and whereby upon return motion of the cam, the resiliency of the blade provides a snap action motion of the cam when the abrupt working surface of the cam returns to the. offset portion of the switch blade.

8. In a timing mechanism, the combination of, a timing motor, a timing shaft, means for rotating the timing shaft in one direction to a predetermined setting, said timing motor being arranged to rotate the timing shaft inthe opposite direction, a cam mounted for free rotation on an axis spaced from and parallel with the timing shaft, means comprising a lost motion connection between said timing shaft and; cam, said lost' motion connection being constructed andarranged to cause the cam to rotate in one direction and assume a first angular position when the timing shaft is set for operation of the timing mechanism and to cause said cam to rotate in the opposite direction and assume a second angular position when the timing shaft returns to the off position, a switch blade anchored at one end and carrying a contact, a second contact cooperating with first contact, said switch blade being biased in a direction tending to open the contacts, and provided with an offset extending oppositely from its contact, said cam being located on the side of the switch blade opposite the contacts and being provided with an abrupt working surface arranged to act on the offset for causing movement of the blade against its bias for closing the contacts as the cam is rotated from said second anqular position to said first angular position, said abrupt working surface of the cam reaching the top of the offset when in said first angular position, whereby the component of force of the switch blade tending to cause reverse rotation of the cam becomes neutralized, said lost motion drive means permitting snap movement of the cam in the reverse direction under the bias of the switch blade, thus permitting snap movement of the switch blade in contact opening direction.

References Cited in the file of this patent UNITED STATES PATENTS 1,171,596 Conrad et a1. Feb. 15, 1916 1,536,145 Royal May 5, 1925 2,039,568 Tamsitt May 5, 1936 2,059,712 Schellenger Nov. 3, 1936 2,488,110 Aitken Nov. 10, 1949 2,503,082 Tuttle Apr. 4, 1950 

